1. Field of the Invention
The present invention relates to a device for dynamically controlling an access to the disk array of a disk array device, constituting a plurality of disk arrays by combining the disk devices of a disk device group and a method thereof.
2. Description of the Related Art
Conventionally, in order to improve the performance, such as an access time, flexibility in composition, and the like, of a disk array device, a plurality of I/Fs (hereinafter called “device adapter (DA)”) for accessing a disk device group is provided, and the disk device group is accessed via one of the DAs.
FIG. 1 shows the major units of the conventional disk array device.
The disk array device shown in FIG. 1 comprises a disk device group 90 composed of a plurality of disk devices, Das 91 and 92, which are I/Fs for accessing this disk device group 90 and a disk array controller 93 for controlling a data access between an information processing device 94 and the disk device group 90 and the entire array device.
The disk device group 90 shown in FIG. 1 is constituted by a plurality of print-wired boards with a plurality of disk devices. Hereinafter the print-wired board is called “slot” and its position is indicated by its “slot number”. A unique logical number (hereinafter called “RAID number”) is also assigned to each of redundant arrays of inexpensive/independent disks (RAID). Foe example, RAID number #00 is assigned to a disk device mounted on the print-wired board whose slot number is #00.
In this case, which DA takes charge of which RAID is generally determined uniquely by its slot number or a RAID number. For example, which DA that takes charge of which RAID is uniquely determined by whether the slot number or RAID number is odd or even.
Japanese Patent Application No. H06-124175 discloses a semiconductor disk device capable of realizing writing speed equivalent to or higher than that of a hard disk device by simultaneously implementing data transfer from the outside to buffer memory, data transfer from the buffer memory to flash memory and the erasure of the flash memory.
Japanese Patent Application No. 2002-116936 discloses a disk array device for equalizing a load due to the read requests of a plurality of HDDs and improving the response performance of a disk array device.
However, in the above-described method, unless disk devices must be consecutively mounted on the disk device mounting slots from one end to the other, there will be unbalance among RAIDs taken charge of by DAs and unbalance among the loads of the DAs. For example, disk devices are mounted every another slot, loads are charged only on DAs with odd (or even) slot numbers and no load is charged on the other slot numbers. Therefore, only performance for one DA can be effectively used, which is a problem.